Can I attach a scsi dds-3 tape drive to a HP l-1000 without rebooting?

[Leon Allen]

We are your typical small (tiny) cash strapped gov dept. We have 1 dds-3 dat tape drive (HP C1537A) which we share between 3 hp-l series (9000/800/L1000-44) servers by physically attaching to servers as needed.

I ordinarily have to reboot the server to 'see' the drive after I attach it. This is a nuiscence, and disruptive.

Is there a better way?

[Ted Ellis_2 · Accepted solution]

once you attach it to the server, have you tried to run ioscan? You may also try "insf -e" to rebuild the server device files and then rerun ioscan.... Our L1000 supports hot swapping its DDS-3 drive.

Ted

[Leon Allen]

Is that ioscan -funC ?

I'll give it a go and let you know how we go (today or tomorrow)

[Michael Tully]

Although we are not a government department, I use one DDS3 drive to create make_recovery tapes on a number of systems. Once the drive has been attached, just run 'ioscan' so that the system recognises it. Once it has (another ioscan will confirm it) all you need to do is run 'insf -e' to create a valid device file. Once this has been done, all you will need to do is plug it in and use on each server.

[Marino Meloni_1]

Hi,
These are not hotSwap devices
even if it work, I didn't suggest you to connect or disconnect such a kind of unit without powering down the server, the problem is electricaly related and a voltage spike at disconnect time could generate extra current in the related line and blow up scsi interface.
Reconnecting the device is very easy to let the pins of the connector get in contact with the grounding shield of the connector itself.
Knowing this you can evaluate if you could deal with the risk
bye
marino

[Ted Ellis_2]

had our HP rep on-site to swap out a bad DDS-3 drive... the server is an L1000 and no reboot was required at all.

AS for the ioscan question... ioscan -funC does not actually perform a fresh scan, but reports the devices available based on the last scan

simply entering ioscan will rerun everything and the insf -e is only required if the device file is not present

Ted

[Marino Meloni_1]

I apologize for the error, I was not considering the l1000 but the lp1000 which is a netserver
marino

[Michael Lampi]

Meloni is still right. There is a definite risk associated with hot plugging a peripheral into an active SCSI bus.

If the particular bus in question is not actively being used by any other peripheral, then it is possible to connect your DDS-3 drive to the bus, perform the ioscan and insf commands, and do what you want to do.

However, I would strongly recommend that you use a pass-through SCSI terminator so that you do not have to disconnect and reconnect the terminator each time. This assumes, of course, that you have other external SCSI devices on that bus. If you don't, then make sure that the DDS-3 drive already has its terminator in place before connecting the external cable to the server.

Also, make sure that you have plugged in the power supply to the tape drive to the mains. This will ensure that any static electricity buildup in the DDS drive cabinet is dissipated through the ground rather than through the SCSI cable. Of course, the DDS drive should be OFF when you do this.

Even taking all these precautions, it is possible to damage the SCSI controller on your server. After 5 to 7 years of doing this sort of thing on a regular (daily/hourly) basis with half a dozen workstations, I managed to break one (1) HP low speed SCSI controller. I then went and bought an HP PCI LVD/SE SCSI controller and continued on my merry way. :-)

When you guys get more $$$, then you can buy some new or used DDS-3 drives and not play these games.

Optionally, access the DDS drive remotely over your LAN.

[Leon Allen]

Lots of useful input - thanks heaps one and all!

I am inclined to 'give-it-a-go' - being mindful of the spikes, and the odds as outlined above. The passthrough scsi terminator sound like a good idea. My preferred option is more dives, but.......

Accessing the dds-3 through the network? Now thats a whole new ball game! Our primary use is making system recovery tapes - I suspect access via the LAN is a no-can-do. But- for one-off backups; archiving; temporary offline storage.....sounds great! I might start another thread on that (accessing a dds-3 tape dive via the LAN? how to do it?)

[Leon Allen]

OK - Its done. I:
* powered down the dds-3
* left it connected to the power (earthing it)
* noted no other activity on the scsi
* carefully unplugged the scsi cable from the back of the server
* carefully plugged it into the scsi port of the next server
* powered the unit up
did an ioscan
* did a ioscan -C tape -fun - just to make sure I could see the device.
* then happily did a mediainit -v /dev/rmt/0mb

and right now am using ignite to build a system recovery tape.

Seemed to work (on this occassion)

Again - thanks to all!